An attractive emerging clinical approach for augmenting wound healing (or therapeutic treatment in general) is the rapidly expanding clinical and surgical use of recombinant or autologous growth factors for improved therapeutic outcomes. Examples of areas where such wound healing compositions are useful include intractable decubitus and pressure ulcers; orthopedic bone defect repair and bone ingrowth in fixation and implantation procedures; plastic and maxillofacial surgery; burn skin grafts; connective tissue repair; periodontal surgery, etc., as described by: Knighton D R, Surgery, Gynecology & Obstetrics 170: 56-60. 1990; and in Slater M, J Orthop Res 13: 655-663. 1995.
The widespread clinical and surgical acceptance of growth factor-based wound healing therapies are currently limited to some degree by the high cost associated with both recombinant and autologous growth factor healants, and the additional inconvenience of processing autologous cells intraoperatively. Although only few controlled comparisons have been made between autologous growth factor cocktails and purified protein recombinant growth factors for wound healing effectiveness, a single recombinant growth factor may be less effective in many wound healing applications than a combination of natural growth factors (PDGF, VEGF, TGF, EGF, etc.) present in platelets as suggested by Cromack D T, J Trauma. 30: S129-S133, 1990. To that end, several potentially therapeutic growth factor compositions have been developed that contain more than one growth factor. However, the clinical applicability of some of these healants can be limited by high cost and inconvenience of obtaining growth factor compositions for use.
For example, current autologous growth factor harvesting systems are expensive and rely on technician-intensive blood processing to generate platelet rich plasma (PRP) prior to the additional steps required to harvest platelets to desired therapeutic concentrations, e.g., by centrifugation, by gel filtration, or by ultrafiltration. Laboratory separation by gravity has also been used, though time constraints make this a less desirable approach. In any case, previous methods of obtaining platelet-rich growth factors have relied upon the use of relatively expensive and cumbersome laboratory equipment, and have not been readily adaptable for use in environments where such laboratories are not accessible or cannot be used in a cost-effective manner.
The process described herein allows for a cost-effective, timely, and convenient technique for isolation and concentration of autologous or homologous platelets with included active growth factors. These cells may be harvested from small volumes of patient blood preoperatively, intraoperatively, perioperatively, or for outpatient procedures to allow for convenient and sustained delivery of growth factors to effectively promote healing.